VB.NET获取文件默认图标的方法

Private Structure SHFILEINFO
  Public hIcon As IntPtr
  Public iIcon As Integer
  Public dwAttributes As Integer
  <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=260)> _
  Public szDisplayName As String
  <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=80)> _
  Public szTypeName As String
End Structure
Private Declare Auto Function SHGetFileInfo Lib "shell32.dll" _
    (ByVal pszPath As String, _
     ByVal dwFileAttributes As Integer, _
     ByRef psfi As SHFILEINFO, _
     ByVal cbFileInfo As Integer, _
     ByVal uFlags As Integer) As IntPtr
Private Const SHGFI_ICON = &H100
Private Const SHGFI_SMALLICON = &H1
Private Const SHGFI_LARGEICON = &H0
Private nIndex = 0
Private hImgLarge As IntPtr 'The handle to the system image list.
Private Function GetLargeIcon(ByVal FilePath As String) As System.Drawing.Icon
  Dim fName As String
  Dim shinfo As SHFILEINFO
  shinfo = New SHFILEINFO()
  shinfo.szDisplayName = New String(Chr(0), 260)
  shinfo.szTypeName = New String(Chr(0), 80)
  fName = FilePath
  hImgLarge = SHGetFileInfo(fName, 0,
  shinfo, Marshal.SizeOf(shinfo),
  SHGFI_ICON Or SHGFI_LARGEICON)
  Dim myIcon As System.Drawing.Icon
  myIcon = System.Drawing.Icon.FromHandle(shinfo.hIcon)
  Return myIcon
End Function
Private Function GetSmallIcon(ByVal FilePath As String) As System.Drawing.Icon
  Dim fName As String
  Dim shinfo As SHFILEINFO
  shinfo = New SHFILEINFO()
  shinfo.szDisplayName = New String(Chr(0), 260)
  shinfo.szTypeName = New String(Chr(0), 80)
  fName = FilePath
  hImgLarge = SHGetFileInfo(fName, 0,
  shinfo, Marshal.SizeOf(shinfo),
  SHGFI_ICON Or SHGFI_SMALLICON)
  Dim myIcon As System.Drawing.Icon
  myIcon = System.Drawing.Icon.FromHandle(shinfo.hIcon)
  Return myIcon
End Function